1. Field of the Invention
This invention relates to a diesel engine crankcase lubricating composition which exhibits improved resistance to corrosion and oxidation. More particularly, this invention relates to a novel corrosion and oxidation resistant diesel engine crankcase lubricating composition comprising a major amount of a hydrocarbon lubricating oil and a minor amount of the reaction product of an n-acyl sarcosine reactant and a substituted or unsubstituted heterocyclic azole reactant. The instant invention is particularly useful as a lubricant in large diesel engines such as marine and railway diesel engines.
2. Information Disclosure Statement
As is well known to those skilled in the art, lubricating oils must be characterized by resistance to oxidation and corrosion inhibition. Since the oils used as lubricants in the crankcases of large diesel engines, such as marine and railway diesel engines, are subject to unique conditions of operation, special attention must be directed to the potential problems which are to be encountered.
In addition, the advent of new, more fuel efficient railway diesel engines has put a greater demand on the oxidation resistance of railway diesel lubricants. Oxidized lubricants may lead to increased corrosive attack of engine metal surfaces; consequently, lubricants employed in newer railway diesel engines must be changed more frequently to prevent such corrosive attack.
In view of the above, diesel engine lubricant compositions have previously been specifically formulated containing anti-wear additives, demulsifying agents, oxidation and corrosion inhibitors and other additives. In particular, oxidation and corrosion-inhibited diesel engine lubricant formulations containing azole compound reaction products have been developed. For example:
Co-assigned U.S. patent application Ser. No. 115,491, filed Nov. 2, 1987 (D#78,549) (Sung et al.) discloses an oxidation and corrosion-resistant diesel engine lubricant composition comprising a major amount of a hydrocarbon lubricating oil and a minor amount of the reaction product prepared by first reacting a hydroxybenzoic acid with a polyoxyalkylene polyol to produce an ester, and thereafter reacting the esterification product with an aldehyde or ketone and a substituted or unsubstituted heterocyclic azole to form the final reaction product;
Co-assigned U.S. Pat. No. 4,705,642 (Sung et al.) discloses a haze, oxidation, and corrosion-resistant diesel engine lubricant composition which comprises a major amount of a hydrocarbon lubricating oil and a minor amount of the reaction product of an anhydride compound, a hydrocarbon-substituted mono primary amine or ether amine, and a nitrogen-containing heterocyclic azole or polyalkylene polyamine compound;
Co-assigned U.S. Pat. No. 4,464,276 (Sung et al.) describes the preparation of novel polyoxyalkylene polyamine-triazole complexes and their use in diesel lubricant compositions as antioxidants and corrosion-inhibitors; and
Co-assigned U.S. Pat. No. 4,285,823 (Sung et al.) discloses a diesel engine lubricant composition comprising a corrosion inhibitor which is the reaction product of an N-alkyl-1,3 propane diamine, formaldehyde, and a 5-aminotetrazole.
The corrosion-inhibiting properties of N-acyl sarcosine reaction products in motor fuel compositions are also known to those skilled in the art. For example, the corrosion-inhibiting properties in alcohol and gasoline-alcohol compositions of the reaction product of (i) compounds including N-acyl sarcosines and (ii) aminotetrazoles are disclosed in co-assigned U.S. Pat. No. 4,445,907 (Sung). In addition, the corrosion-inhibiting properties in motor fuel compositions of the reaction product of (i) an N-acyl sarcosine reactant and (ii) a polyalkylene polyamine reactant are disclosed in co-assigned U.S. Pat. No. 4,305,731 (Sung et al.).
It is an object of this invention to provide a novel diesel engine lubricant composition. It is another object of this invention to provide a novel lubricant composition, suitable for use in large marine and railway diesel engines, characterized by its resistance to oxidation and corrosion. It is yet another object of this invention to provide a method of preparing such a diesel engine lubricant composition, as well as a method of inhibiting the oxidation of a diesel engine lubricant composition.
It is a feature of this invention that a diesel engine lubricant comprising a major amount of a hydrocarbon lubricating oil and a minor amount of the reaction product of an N-acyl sarcosine reactant and a substituted or unsubstituted heterocyclic azole reactant is characterized by its resistance to oxidation and corrosion. It is another feature of this invention that such a diesel engine lubricant composition is particularly suitable for use in large marine and railway diesel engines.
It is an advantage of this invention that the corrosion of diesel engine metal surfaces is reduced by employing this invention as a lubricant. It is another advantage of this invention that it may be changed less frequently than other conventional diesel engine lubricants.